In the related art, a driving support device including a support starting unit configured to start support for a lane change, a detecting unit configured to detect a relative distance and a relative speed between a host vehicle and another vehicle, a calculation unit configured to calculate a degree of collision risk with respect to the other vehicle when the host vehicle changes lanes on the basis of the relative distance and the relative speed, a first determination unit configured to determine whether to change lanes on the basis of the relative distance, the relative speed, and the degree of collision risk, a decision unit configured to decide a target space for lane change on the basis of the relative distance and the relative speed when it is not possible to change lanes, a second determination unit configured to determine whether there is a space in which lane change is possible in the target space, a setting unit configured to set a target speed toward a lane change waiting position when there is no space and set a target speed toward a lane changeable position when there is a space, and a control unit configured to perform control such that a speed of the host vehicle becomes a target speed is known (for example, refer to Patent Literature 1).